1. Field of the Invention
The present invention relates to a home-zone service in a mobile radio communication system, and more particularly to an apparatus and method for registering the home-zone location in a portable radio telephone.
2. Description of the Related Art
Under the current billing scheme, a connection charging fee relating to a wireless service fee is higher than a wired service fee. Naturally, mobile subscribers will attempt to use the wired service if they are inside their home or office to save money under the current billing practice. If such a billing difference were not practiced, it would not be necessary for the mobile telephone subscriber to separately own a wired telephone set.
To attract more subscribers, phone companies are offering a unique service feature known as the home-zone service, which allows mobile subscribers to designate a specified region to benefit the lower billing rate when using their mobile phones. Thus, the boundary of a home-zone service can be predetermined and a different billing rate when the mobile phone is used inside the home zone. For example, if a mobile telephone subscriber designates his/her house as his/her home zone, a lower charging rate equivalent to a wired connection call is billed. Other different features and options are also available in the home-zone service.
FIG. 1 is a block diagram illustrating the construction of a mobile radio communication system. The reference numeral 20 denotes a radio frequency (RF) equipment, such as a base transceiver station (BTS) for performing radio communication with the mobile terminal 10 of a subscriber. A base station controller (BSC) 30 controls the base transceiver station 20 to perform the call processing operation or the channel allocation. A mobile switching center (MSC) 40 serves to link the base station controller 30 to a public switched telephone network (PSTN) 50 or another base transceiver station. The mobile switching center 40 obtains the subscriber information from a visitor location register (VLR) 60 and a home location register (HLR) 70. The visitor location register 60 temporarily stores information relating to the subscriber. The home location register 70 also stores therein the subscriber information. Here, the subscriber information relates to terminal information, subscriber information, subscriber home-zone information, additional service information, etc.
FIG. 2 illustrates the boundary of a home-zone service area. As shown in FIG. 2, the home-zone service area is determined by three base transceiver stations 21 to 23. The respective base transceiver station is divided into three sectors α, β, and γ. Thus, the home-zone list for the mobile terminal 10 can be further narrowed using the sector α of the base transceiver station 21, the sector β of the base transceiver station 22, and a sector γ of the base transceiver station 23.
FIG. 3a illustrates the process of generating a home-zone list during the registration process. Information relating to the home-zone list of a subscriber is registered in the home location register (HLR). The mobile switching center (MSC) determines whether a particular mobile terminal is located inside or outside the home zone using cell identification (cell_ID), sector identification (sector_ID), and round trip delay (RTD) information included in the location update message signal transmitted from the mobile terminal. Then, the MSC transmits its determination to the base transceiver station (BTS). The BTS in turn transmits the same determination back to the mobile terminal so that a subscriber can be informed accordingly.
FIG. 3b illustrates the process of referring to the home-zone list when a call is originated or terminated. If a mobile terminal originates a call, the mobile switching center transmits a channel assign request message, which includes the home-zone list of the subscriber and the mobile phone information. The base station controller (BSC), upon receiving this request, determines whether the mobile terminal is located within the home zone by comparing the current location of the subscriber with the information stored in the home-zone, then informs the mobile switching center (MSC) of the determination via a channel assign complete message. The MSC maintains the corresponding call if it is determined that the mobile terminal is located inside the home zone area based on the information received from the base station controller but releases the call otherwise.
Sometimes, a subscriber can restrict the use of the mobile terminal to only within the home zone area. In this case, if the subscriber is located outside the home zone, the call connection can not be performed. If such a service is requested by the subscriber, the current MSC is designed to page the mobile terminal to notify the subscriber and allocates a channel to the corresponding mobile terminal. Thus, such unnecessary determination causes waste of resources in the present system. This waste occurs because the MSC is not notified by the mobile terminal when the terminal moves outside the home zone area.